The liver in known to be involved in the selective transport of serum IgA into the bile. The role of the liver in the removal from the circulation of antigens bound IgA molecules in the form of IgA-immune complexes will be investigated. The experimental model to be used will involve mouse myeloma or hybridoma antibodies of IgA, IgM or IgG class specific for dinitrophenyl groups (DNP) and antigens of various physico-chemical properties conjugated with DNP. The selectivity of the hepato-biliary tranport will be related to 1) the immunoglobulin class and molecular properties of the antibody and of the immune complex and 2) the characteristics of the antigen. The unique role of the liver in the removal of IgA-containing immune complexes will be studied by comparing the efficiency of hepato-biliary transport with other secretory tissues such as intestines and mammary and salivary glands. The cellular mechanism of the IgA-mediated antigen removal by the liver will be investigated to determine the type(s) if liver cells, the cell surface receptors and cellular pathways involved. The importance of hepato-biliary transport in the removal of antigens absorbed in the gastrointestinal tract will be investigated.